Liquid crystal display apparatus and method of manufacturing the same

ABSTRACT

An object of the invention is to provide an inexpensive method of manufacturing a liquid crystal display apparatus having a low resolution by utilizing a TFT substrate adapted for a high-definition liquid crystal display apparatus. The liquid crystal display apparatus having a low resolution is realized in an inexpensive way by using the TFT substrate adapted for a high-definition liquid crystal display apparatus and by combining a new color filter substrate and driver ICs suited to a new driving method, the new color filter substrate being formed such that one pixel group is formed by pixels of a color filter substrate wherein the number of pixels is the product of three by an integer.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a division of pixels of colorfilters used in a color liquid crystal display panel or the like.Particularly, the invention relates to the correlation between ahigh-definition liquid crystal panel and a low-price AV (audio-visual)liquid crystal television panel as well as to a method of manufacturingthese two modules correlated to each other.

[0003] 2. Description of the Related Art

[0004] Conventionally, in manufacturing both a high-definition liquidcrystal display panel and a low-price AV liquid crystal televisionpanel, TFT (thin film transistor) substrates, which have differentdesign specifications in resolution or a number of pixels, are formed onrespective glass substrates from the beginning, and then a color filtersubstrate, driving circuit and driving ICs are formed to matchrespective TFT substrates and then they are assembled together.

[0005] When a high-definition liquid crystal panel and a low-price AVliquid crystal television panel are manufactured, even if they have thesame display sizes and different numbers of pixels, the conventional artdoes not have an idea of using a common TFT substrate by changing thecolor filters, driving ICs and driving circuits.

[0006] Japanese Unexamined Patent Publication JP-A 6-82617 (1994)(Applicant: FUJITSU CO. LTD.) is directed to a method of dividing pixelsin pixel groups each of which is composed of a plurality of color pixelsand discloses that color filters are provided which are capable ofaccommodating to graphics, characters and drawings, respectively. Thoughthe Gazette discloses that a single pixel group consists of three pixelsfor R, G and B having different shapes respectively, it does notdisclose that the scale of each pixel group is changed, namely theresolution is varied by forming one pixel group consisted of pluralpixels of different colors such as R, G, B and like colors wherein thenumber of pixels is the product by a factor of an integer.

[0007] Alternatively, Japanese Unexamined Patent Publication JP-A11-7269 (1999) (Applicant: SONY CO., LTD.) discloses a driving method inwhich pixels arranged in a matrix form over substantially the entirescreen of a panel are laid out, namely a plurality of pixels areallocated to a single pixel group irrespective of the resolution of aninputted video signal in order to provide a display apparatus havingability to accommodate to a plurality of video signals having differentstandards by devising signal processing for a panel having fixed pixelsand a fixed total number of pixels such as a liquid crystal displaypanel or a plasma display panel.

[0008] This Gazette, however, does not disclose that the arrangement ofcolor filters is changed with varying respective resolution.

[0009] In the conventional process for manufacturing both ahigh-definition liquid crystal display panel and a low-price AV liquidcrystal television panel, it is necessary to initially form TFTsubstrates having different design specifications in resolution ornumber of pixel groups, and then form color filter substrates, drivingcircuits and driving ICs such as to match TFT substrates respectively.Thus, member sharing of TFT substrate or the like is not performed.Neither JP-A 6-82617 nor JP-A 11-7269 discloses any art of using a TFTsubstrate adapted for display of high resolution video signals and acolor filter substrate adapted for display of low resolution videosignals which is different from a color filter substrate adapted forhigh resolution thereby providing a panel for display of low resolutionvideo signals.

SUMMARY OF THE INVENTION

[0010] An object of the invention is to provide a liquid crystal displayapparatus capable of being used for both high-definition liquid crystalpanels and low-price liquid crystal television panels, thereby enhancingthe production efficiency and yield of such panels, and a method ofmanufacturing the same.

[0011] The invention provides a liquid crystal display apparatuscomprising a pair of substrates, a plurality of pixel electrodes whichare arranged in a matrix form, formed on one substrate of the pair ofsubstrate, and a plurality of color filters of n (n is an integer of twoor more) number of colors corresponding to the plurality of pixelelectrodes, the plurality of color filters being arranged so that colorfilters of a same color sequentially form m (m is an integer of two ormore) number of columns, wherein n×m×l (l is a natural number) pixelsform one pixel group.

[0012] According to the invention, since one pixel group consists ofn×m×l pixels, when both a high-definition liquid crystal panel and alow-price liquid crystal television panel are manufactured, if they havethe same display size but different numbers of pixels, by using a TFTsubstrate as a common part and using different color filter substrate,driving ICs and driving circuit, it is possible to manufacture both thehigh-definition liquid crystal panel and the low-price liquid crystaltelevision panel by changing only the latter half of a production line,whereby the delivery time can be shortened. Further, since commonalityof components can be achieved, the production efficiency is improved.

[0013] In the low-price liquid crystal panel, since each pixel groupconsists of a plurality of pixels and has an wide area, even if one ofpixels is defective, such a defective pixel is difficult to berecognized visually and hence does not render the one pixel groupdefective. This leads to an improved production yield of liquid crystalpanels, hence, to an improved efficiency in volume production.

[0014] In the case where such a defective pixel forms a black spot, sucha black spot is difficult to be recognized as a defect when the size ofsuch a pixel is approximately the same as that of a pixel for use in ahigh-definition panel. Even where such a defective pixel forms a brightspot, if a bright spot is modified into a black spot, it will be morehardly recognized as a defect, thus leading to a further improvedproduction yield.

[0015] In the invention it is preferable that each of the plurality ofpixel electrodes is provided with a TFT.

[0016] According to the invention, a TFT substrate can be used.

[0017] In the invention it is preferable that the n number of colors arethree primary colors consisting of red (R), green (G) and blue (B).

[0018] According to the invention, it is possible to display a colorimage composed of the three primary colors, namely, R, G and B.

[0019] In the invention it is preferable that the color filters areformed on the other substrate of the pair of substrates.

[0020] According to the invention, the color filters can be formed onthe TFT substrate or the counter substrate.

[0021] In the invention it is preferable that the liquid crystal displayapparatus comprises a driver the same as that used in a liquid crystaldisplay apparatus having color filters of n number of colors arrangedsequentially, and different color filters and controller from those usedin the latter liquid crystal display apparatus.

[0022] According to the invention, in a high-definition liquid crystalpanel and a low-price liquid crystal panel, a common part can be used.

[0023] In the invention it is preferable that the liquid crystal displayapparatus in which the n×m×l pixels form one pixel group is constructedby short-circuiting a bus line extending in the direction of column atevery m pixels or a bus line extending in the direction of row at everyone pixel.

[0024] According to the invention, the number of internal circuits inthe horizontal and vertical drivers can be significantly reduced byshort-circuiting the bus lines.

[0025] The invention provides a method of manufacturing a liquid crystaldisplay apparatus comprising a step of laminating a TFT substrate onwhich a plurality of pixel electrodes are arranged in a matrix form, anda color filter substrate on which a plurality of color filters of n (nis an integer of two or more) number of colors corresponding to theplurality of pixel electrodes, the plurality of color filters beingarranged so that color filters of a same color sequentially form m (m isan integer of two or more) number of columns, to form one pixel groupconsisting of n×m×l (l is a natural number) pixels.

[0026] According to the invention, since one pixel group consists ofn×m×l pixels, when both a high-definition liquid crystal panel and alow-price liquid crystal television panel are manufactured, if they havethe same display size but different numbers of pixels, by using a TFTsubstrate as a common part and using different color filter substrate,driving ICs and driving circuit, it is possible to manufacture both thehigh-definition liquid crystal panel and the low-price liquid crystaltelevision panel by changing only the latter half of a production line,whereby the delivery time can be shortened. Further, since commonalityof components can be achieved, the production efficiency is improved. Inthe low-price liquid crystal panel, since each pixel group consists of aplurality of pixels, even if one of pixels is defective, such adefective pixel does not render the one pixel group defective. Thisleads to an improved production yield of liquid crystal panels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Other and further objects, features, and advantages of theinvention will be more explicit from the following detailed descriptiontaken with reference to the drawings wherein:

[0028]FIG. 1 is a comparative view for comparing mutual manufacturingcomponents of a high-definition liquid crystal module with those of aliquid crystal AV module;

[0029]FIG. 2 is a block diagram showing the overall configuration of ahigh-definition liquid crystal module;

[0030]FIG. 3 is a view showing the arrangement of color filters on acounter substrate in a high-definition liquid crystal display apparatus,in which the diagonally shaded portion is equivalent to one pixel group;

[0031]FIG. 4 is a block diagram showing the overall configuration of anAV display module according to a first embodiment of the invention;

[0032]FIG. 5 is a view showing an example of the arrangement of newcolor filters on a counter substrate of the AV display module used inthe manufacture of the AV display module according to the firstembodiment, in which the diagonally shaded portion is equivalent to onepixel group;

[0033]FIG. 6 is a block diagram showing the overall configuration of anAV display module according to a second embodiment of the invention;

[0034]FIG. 7 is a view showing the arrangement of new color filters on acounter substrate of the AV display module according to the secondembodiment, in which the diagonally shaded portion is equivalent to onepixel group; and

[0035]FIG. 8 is a diagram distinctly explaining a TFT substrate step, acolor filter step, and a latter-half of steps (after the laminatingstep).

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0036] Now referring to the drawings, preferred embodiments of theinvention are described below.

[0037]FIG. 1 is a comparative view for comparing a method ofmanufacturing a low-definition liquid crystal module of the inventionwith that of manufacturing a conventional high-definition liquid crystalmodule, in which method of the invention a TFT substrate identical withthat for a high-definition liquid crystal module is used and a latterhalf of manufacturing steps are slightly different from those of thehigh-definition liquid crystal module.

[0038] The relation between the number of pixel groups in thehigh-definition liquid crystal panel and the number of pixel groups inthe liquid crystal AV panel is ideally such that the number of pixelgroups in the high-definition liquid crystal panel can be divided by afactor of the number of source bus lines or gate bus lines in the liquidcrystal AV panel. Even if there is a remainder, the remainder may beappropriately allocated.

[0039] The manufacturing steps are described as follows.

[0040] First, a high-definition TFT substrate (A) is formed. When thehigh-definition liquid crystal module is to be manufactured, as shown inFIG. 3, the high-definition TFT substrate (A) is laminated as a countersubstrate with color filters wherein one pixel group is formed by colorsR, G and B. For convenience of illustration of the arrangement of colorfilters, FIG. 3 shows gate bus lines 1, source bus lines 2, pixels 3 andTFT devices 5, which are all absent on the counter substrate. Each ofthe pixels 3 is what is called a pixel electrode.

[0041] In turn, as shown in FIG. 2, drivers and controller adapted for ahigh-definition substrate are connected to the high-definition TFTsubstrate (A) to complete the high-definition TFT liquid crystal module.

[0042] In FIG. 1, components of the high-definition TFT substrate modulethus manufactured are indicated schematically in a rectangular blocklabeled “Usual High-Definition Liquid Crystal Module”.

[0043] The following description is directed to two liquid crystal AVmodules having different resolutions (number of pixel groups) and usinghigh-definition TFT substrates as used in the above high-definitionliquid crystal module, which modules are manufactured as a firstembodiment and a second embodiment, respectively.

[0044] First Embodiment

[0045] In the first embodiment, a liquid crystal AV module ismanufactured by changing only the color filters and controller fromamong the components used in the high-definition liquid crystal moduleinto corresponding ones adapted for an AV module.

[0046] As shown in FIG. 5, the high-definition TFT substrate (A) islaminated as a counter substrate with new color filters wherein colorsfor R, G and B are allocated to a corresponding group of pixels and thatone pixel group consists of a plurality of pixels. For convenience ofillustration of the arrangement of color filters, FIG. 5 shows gate buslines 1, source bus lines 2, pixels 3 and TFT devices 5, which are allabsent on the counter substrate. Each of the pixels 3 is what is calleda pixel electrode.

[0047] In this embodiment, an example is shown wherein one pixel groupconsists of pixels of 3 rows×6 columns. However, the invention is notlimited to this value.

[0048] In turn, as shown in FIG. 4, horizontal and vertical drivers usedfor the high-definition TFT are used, a new controller is connected soas to correspond to the arrangement of colors shown in FIG. 5 and theliquid crystal AV module is completed.

[0049] According to this method, the liquid crystal AV module can becompleted by substituting only the new color filters of the colorarrangement shown in FIG. 5 and the new controller shown in FIG. 4.

[0050] Second Embodiment

[0051] In the second embodiment, a liquid crystal AV module ismanufactured by changing the color filters, drivers and controller ofthe components used in the high-definition liquid crystal module intocorresponding ones adapted for an AV module and by short-circuitingterminals of the high-definition TFT substrate on a group basis.

[0052] The high-definition TFT substrate (A) is modified byshort-circuiting the terminals of the source bus lines and gate buslines on a group basis using a photo step. Specifically, in theformation of pixel electrodes, a photomask used to form the pixel groupsof a conventional high-definition panel is substituted with a photomaskwherein terminals are short-circuited on a group basis. Thus, a TFTsubstrate adapted for the purpose can be obtained only by changing onephotomask.

[0053] The TFT substrate thus obtained is shown in FIG. 6. As shown inFIG. 7, the TFT substrate is laminated with a new color filters whereinR, G and B colors are allocated to corresponding pixel groups of pixelsand that one pixel consists of a plurality of pixels. In thisembodiment, one pixel group consists of pixels of 3 rows×6 columns,however, numbers of rows and columns are not limited to these values.

[0054] In turn, new horizontal and vertical drivers corresponding to thenumber of short-circuited bus lines are connected to the resultingstructure to complete the liquid crystal AV module. According to thismethod, the liquid crystal AV module can be obtained by substitutingonly the new color filters as shown in FIG. 7 and the new horizontal andvertical drivers and new controller as shown in FIG. 6 for thecorresponding ones used in the high-definition liquid crystal module andmerely short-circuiting the bus lines of the high-definition TFTsubstrate.

[0055] According to the second embodiment, the number of internalcircuits in the horizontal and vertical drivers can be significantlyreduced by short-circuiting of the bus lines.

[0056] In the case of a pixel group consisting of 3 rows×6 columns, forexample, the number of internal circuits required in the new horizontaldriver is three, which would otherwise be six, and the number ofinternal circuits required in the new vertical driver is one, whichwould otherwise be three. Such a reduction in the number of internalcircuits can be easily realized by arranging the color filters intogroups in each of which color filters of the same color are locatedside-by-side according to this embodiment.

[0057] In the case of the color filter arrangement shown in FIG. 3 inwhich a set of three color filters for R, G and B forms one pixel group,short-circuiting of the bus line interconnecting color filters of thesame color would make the wiring structure complicate due to thepresence of color filters for different colors, hence, increase thenumber of steps for realizing such a complicated wiring structure.

[0058] Though the bus lines are short-circuited on the TFT substrate inthe second embodiment, it is possible to employ an arrangement such thatshort-circuiting is made in the drivers. In this case, the number ofoutput terminals from the drivers is the same as that of the firstembodiment. For the same reason as that described above, the colorfilter arrangement in this embodiment enables easy short-circuiting.

[0059] Further, though the bus lines of both the new horizontal driverand the new vertical driver are short-circuited in the secondembodiment, it is possible to short-circuiting the bus lines of any oneof them. Taking the one-line inverse drive to inverse the polarity of avideo signal at every one row for instance, the bus lines of the newhorizontal driver may be short-circuited, while the bus lines of the newvertical driver may not be short-circuited but configured to beindividually operated in sequence for ensuring an improved displayquality.

[0060] In this case also, there results an advantage that the number ofinternal circuits in the new horizontal driver is reduced. Though thecolor filters for R, G and B are used in the embodiment, the inventionis not limited to these colors. The embodiment is applicable for colorfilters with two or more colors.

[0061] Further, though the color filters are formed not on the TFTsubstrate side but on the counter substrate side in the embodiment, theymay be formed on the TFT substrate side.

[0062] In this case, the liquid crystal AV module can be manufactured byusing a TFT substrate on which color filters are formed corresponding tothe liquid crystal AV panel as a high-definition TFT substrate on whichcolor filters are not formed.

[0063]FIG. 8 is a flowchart of the manufacturing steps of a liquidcrystal cell, including a TFT substrate forming step, a color filter(CF) substrate forming step, and a latter half of steps. With referenceto FIG. 8, the steps up to the completion of the liquid crystal cell aredescribed below.

[0064] First, initial cleaning is performed (S1); an alignment film isformed on the TFT substrate having TFT devices formed on a glasssubstrate (S2); the alignment film is rubbed (S3) to allow liquidcrystal molecules to easily align in a predetermined direction; a pastefor provisional fixing is applied onto the substrate (S4); and spacersare dispersed (S5). The color filter substrate is also formed with analignment film, following by rubbing; and a sealing resin is appliedonto the substrate (S6).

[0065] Subsequently, the both substrates are laminated together bybonding (S7); after the sealing resin is set (S8); and the cells areseparated from each other by cutting the glass substrates (S9). In turn,a liquid crystal composition is injected into each cell by utilizing avacuum and the injection port is sealed with a resin (S10); and finallycleaning (S11) and inspection (S12) are performed to complete eachliquid crystal cell.

[0066] The remainder of manufacturing steps after laminating the bothsubstrates is referred to as the “latter-half of steps”. Drivers and acontroller are formed in the liquid crystal cell thus manufactured tocomplete a liquid crystal module.

[0067] The invention may be embodied in other specific forms withoutdeparting from the spirit or essential characteristics thereof. Thepresent embodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription and all changes which come within the meaning and the rangeof equivalency of the claims are therefore intended to be embracedtherein.

What is claimed is:
 1. A liquid crystal display apparatus comprising: apair of substrates; a plurality of pixel electrodes which are arrangedin a matrix form, formed on one substrate of the pair of substrates; anda plurality of color filters of n (n is an integer of two or more)number of colors corresponding to the plurality of pixel electrodes, theplurality of color filters being arranged so that color filters for asame color sequentially form m (m is an integer of two or more) numberof columns, wherein n×m×l (l is a natural number) pixels form one pixelgroup.
 2. The liquid crystal display apparatus of claim 1, wherein eachof the plurality of pixel electrodes is provided with a thin filmtransistor.
 3. The liquid crystal display apparatus of claim 1, whereinthe n number of colors are three primary colors consisting of red, greenand blue.
 4. The liquid crystal display apparatus of claim 1, whereinthe color filters are formed on the other substrate of the pair ofsubstrates.
 5. The liquid crystal display apparatus of claim 1,comprising: a driver the same as that used in a liquid crystal displayapparatus having color filters of n number of colors arrangedsequentially, and different color filters and controller from those usedin the latter liquid crystal display apparatus.
 6. The liquid crystaldisplay apparatus of claim 1, the liquid crystal display apparatus inwhich the n×m×l pixels form one pixel group being constructed byshort-circuiting a bus line extending in the direction of column atevery m pixels or a bus line extending in the direction of row at everyone pixel.
 7. A method of manufacturing a liquid crystal displayapparatus comprising: a step of laminating a thin film transistorsubstrate on which a plurality of pixel electrodes are arranged in amatrix form, and a color filter substrate on which a plurality of colorfilters of n (n is an integer of two or more) number of colorscorresponding to the plurality of pixel electrodes, the plurality ofcolor filters being arranged so that color filters of a same colorsequentially form m (m is an integer of two or more) number of columns,to form one pixel group consisting of n×m×l (l is a natural number)pixels.